Rheology of Sandy Polyacrylamide Gels: Application to Conformance in Cold Production
Notice bibliographique
Résumé
Abstract In western Canada, many cold production wells must be prematurely abandoned due to watering-out. High permeability channels (wormholes) are known to develop during cold production. Tracer tests and wormhole growth experiments and simulations suggest that open (sand-free) channels form within the wormholes once they reach a certain length. Wormholes often break into water zones leading to premature abandonment of many wells. Different sandy polyacrylamide gel systems, developed for blocking these open channels, have been used as treatments, and whose results are reviewed here. These systems combine good injectivity with higher strength, as tested in the lab. In addition, a series of viscosity, settling rate, and gel strength tests were performed for different sand concentrations, shear rates, polymer concentrations, molecular weight, and salinity. A promising sandy polymer gel system for water shut-off applications in cold production is described. Introduction Cold production of heavy oil is a non-thermal process in which sand and oil are produced simultaneously. The drive mechanism is generally thought to be solution gas drive. The oil is widely believed to be drained from the reservoir through highly permeable channels, called wormholes, which develop by erosion of the sand when the pressure gradient at the tip of the perforations reaches a critical value. The development of high permeability channels can explain:the short travel time (within hours) of fluorescein dye tracers between wells up to 2 km apart(1);the caliper measurements of Elkins(2) showing wellbore enlargement over only a short length along the vertical well;the relatively low pressures observed during injectivity tracer tests(3);rapid steam communication between certain wells(4,5); and,radioactive tracer tests by Pan Canadian(6) showing tracer penetration over a thin (1 m) thick zone within a 7 m pay zone. The development of wormholes can also explain the high sand cuts at the start of cold production [30% to 40%(7), 10% to 50%(2), 20% to 30%(8)] followed by a sharp decrease in sand cuts to nearly constant values in the range of 0.5% to 1%(7), 0.1 % to 2%(2), and less than 5%(8) after a period of six months to one year. Based on experiments(9) and numerical simulations(10) of wormhole growth, the high sand cuts would occur during the initial growth regime when the wormhole is completely filled with sand. The presence of an open channel within wormholes was strongly suggested by the fluorescein tracer dye study by Amoco(1) in which the dye was injected in one well and was produced from a neighbouring well 400 m away without any loss in concentration. Since the flourescein dye could be easily adsorbed on the surface of a porous medium, this indicated that the dye flowed through an open (sand-free) channel. Numerical calculations(10) indicate that as the wormholes get longer, more oil is drained into the wormholes. Therefore, the flow rate along the wormhole would increase starting from the tip of the wormholes towards the well.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».